This feature has been removed from the Web standards. Though some browsers may still support it, it is in the process of being dropped. Do not use it in old or new projects. Pages or Web apps using it may break at any time.
<isindex> is an obsolete HTML element that puts a text field in a page for querying the document.
<isindex> was providing a single line text input for entering a query string. When sent, the server would return a list of pages matching the query. It supports depended on both the browser and the server to react to the query.
<isindex> is deprecated as of HTML 4.01, because the same behaviour can be achieved with an HTML form.
Like all other HTML elements, this element accepts the global attributes.
- This attribute adds its value as a prompt for text field.
- This attribute can be used to send the query to a different URL. Action is not defined by W3C.
<head> <isindex prompt="Search Document... " /> </head>
On November 1992, indexes as links rather than documents started by Dan Connolly who is pushing the idea that indexes are more links than documents. In this thread, different type of solutions are proposed. The question of forms for making queries is mentioned in reference to Dynatext browser: "The browser displays toggle buttons, text fields etc. The user fills in the fields, clicks OK, and the query results come up in the table of contents window."
A thread about isindex in November 1992, Kevin Hoadley questioned the need for an isindex element and proposed to drop it. He proposed to have instead an input element (idea supported by Steve Putz). Tim Berners-Lee explains the purpose of isindex resulting in aggregated search results. Kevin replies that he doesn't like the boolean nature of isindex and would prefer a system where everything is searchable and proposes to extend the current WWW Framework with a specific httpd configuration and defined that some URIs mapping create search queries.
In 2016, it has been proposed to remove
isindex from the specification.
- HTML5 classifies it as a non-conforming feature.
- ISINDEX element deprecated in HTML 4.01
- ISINDEX in HTML 3.2
- ISINDEX in HTML 2.0 as well the description of the behavior in Queries and Indexes (HTML 2.0)
- ISINDEX in HTML+